Steerable direct myocardial revascularization catheter

ABSTRACT

A steerable direct myocardial revascularization catheter comprises a catheter body, a control handle, a tip section, and a means for deflecting the tip section by manipulation of the control handle. The catheter body has an outer wall, proximal and distal ends, and at least one lumen extending therethrough. The control handle is fixedly attached to the proximal end of the catheter body. The tip section comprises flexible tubing having proximal and distal ends and at least one lumen extending therethrough. The proximal end of the tip section is fixedly attached to the distal end of the catheter body. The catheter also comprises a tip electrode mounted at the distal end of the tip section. The tip electrode has a distal face and an optic fiber lumen therethrough. An electrode lead wire is electrically connected to the tip electrode. The lead wire extends through a lumen in the tip section, through a lumen in the catheter body and into the control handle. The catheter further comprises an optic fiber comprising a core, a metallized cladding and a protective jacker. The optic fiber has a distal end and a proximal end and extends through a lumen in the catheter body and a lumen in the tip section and into the optic fiber lumen of the tip electrode. The distal end of the optic fiber is substantially flush with the distal face of the tip electrode.

FIELD OF THE INVENTION

The present invention relates to steerable catheters which areparticularly useful in direct myocardial revascularization procedures.

BACKGROUND OF THE INVENTION

Direct myocardial revascularization (DMR), also referred to aspercutaneous myocardial revascularization, is a technique that allowsphysicians to treat patients who have sustained a myocardial infractionby burning channels in the myocardium that has been determined to beischemic heart tissue. The channels, which are burned by a laser, allowfor angiogenesis, i.e., the formation of blood vessels.

Several myocardial revascularization procedures are known that requirethat the chest wall be opened to access the heart muscle with laserdevices. The procedures are not very desirable, as they require majorsurgery that can result in severe complications. Aita et al., U.S. Pat.No. 5,389,096, describes a procedure for performing myocardialrevascularization percutaneously by inserting a guidable elongatedflexible lasing apparatus, such as a catheter, into a patient'svasculature. The distal end of the catheter is guided to an area in theheart to be revascularized. The inner wall of the heart is thenirradiated with laser energy to cause a channel to be formed from theendocardium into the myocardium.

For obvious reasons, DMR catheters require the physician to have morecontrol and information than other catheters having an optic fiber, suchas ablation catheters. Aita et al. generally describes a DMR catheter.The present invention is directed to an improved DMR catheter whichallows the physician to have greater control and obtain more informationthan the catheter described in Aita el al.

SUMMARY OF THE INVENTION

The present invention provides a steerable catheter particularly usefulin DMR procedures used to treat ischemic heart tissue. The steerable DMRcatheter comprises a catheter body or shaft, a tip section attached tothe distal end of the catheter body and a control handle attached to theproximal end of the catheter body. A puller wire is anchored at itsproximal end in the control handle and extends through a lumen in thecatheter body and a lumen in the tip section and is anchored at or aboutthe distal end of the tip section. Manipulation of the control handleresults in deflection of the tip section. An optic fiber suitable fortransmission of laser energy extends through the control handle,catheter body and tip section, the distal end of the optic fiber beinggenerally flush with the distal end surface of the tip section. Theproximal end of the optic fiber extends proximally from the controlhandle to a suitable connector which connects the optic fiber to asource of laser energy. The optic fiber is used to transmit laser energyfor creating channels, i.e. blind holes, in the heart tissue whichinduces revascularization.

In a preferred embodiment of the invention, the tip section of the DMRcatheter comprises an electromagnetic sensor. The electromagnetic sensoris connected to a circuit board by means of a sensor cable which extendsproximally through the tip section, catheter body, and control handle.The circuit board is preferably housed in the handle. Signals from thecircuit board are transmitted through a cable to a computer and monitor.The electromagnetic sensor allows a physician to create a visualrepresentation of the heart chamber and to view the location of thesensor, and therefore the catheter tip, within the chamber.

In another preferred embodiment, the DMR catheter comprises a tipelectrode and one or more ring electrodes spaced proximally from the tipelectrode. Each electrode is connected by means of electrode lead wireswhich extend through the tip section, catheter body and control handleto an appropriate connector, and from there, to a suitable monitor. Thetip and ring electrodes allow the electrical activity of the hearttissue to be mapped. In a particularly preferred embodiment of theinvention, the DMR catheter comprises both an electromagnetic sensorwithin the tip section and a tip electrode and one or more ringelectrodes. This combination allows a physician to map the electricalactivity of the heart wall of a particular chamber, e.g., the leftventricle, by means of the tip and ring electrodes to determine ischemicareas and simultaneously to record the precise location of the tipsection within the heart by means of the electromagnetic sensor tocreate a three-dimensional representation of the heart chamber which isdisplayed visually on a monitor. Once an ischemic area has been mapped,the tip section is moved to that area and deflected to allow the opticfiber to be generally normal to the heart wall, and then laser energy istransmitted onto the heart tissue for creating a channel within theheart tissue.

In another aspect of the invention, the optic fiber comprises aprotective jacket, preferably made out of aluminum. The optic fiberextends through the control handle and catheter body and into the tipsection which carries a tip electrode. In the tip section, the opticfiber extends through an optic fiber lumen in the tip electrode, thedistal end of the optic fiber being flush with the distal face of thetip electrode. The aluminum jacket is removed from the distal portion ofthe optic fiber which extends through the tip electrode. This removalavoids the possibility that particles of the aluminum jacket may breakfree into the heart, especially during laser transmission, which couldresult in a stroke. This removal also prevents the possibility of anelectrical short between the aluminum jacket and the tip electrode,which could result in the patient receiving a lethally high voltageduring laser transmission.

In another aspect of the invention, there is provided a DMR catheterhaving an infusion tube which extends from the proximal end of thecatheter body through a lumen in the catheter body and into the tipsection. The distal end of the infusion tube is open at the distal endof the tip section at a position adjacent the optic fiber so thatfluids, including drugs to induce angiogenesis, may be passed throughthe catheter to the heart tissue. In a preferred embodiment, the DMRcatheter comprises an infusion tube and a tip electrode having aninfusion passage adjacent the optic fiber lumen. The infusion tube isconnected to, preferably inserted into, the infusion passage in the tipelectrode so that fluids passing through the infusion tube will enterand pass through the infusion passage in the tip electrode and to theheart tissue. The proximal end of the infusion tube terminates in a luerhub or the like.

In yet another aspect of the invention, the catheter body or shaftcomprises a construction which exhibits improved torsional stability,resulting in improved tip control while minimizing wall thickness. Thecatheter body comprises a single central lumen and is formed by atubular outer wall of polyurethane or nylon with a braided stainlesssteel mesh imbedded in the outer wall. The inner surface of the outerwall is lined with a stiffening tube, preferably made of polyimide orthe like. The use of a polyimide stiffening tube provides improvedtorsional stability while at the same time minimizing the wall thicknessof the catheter. This, in turn, maximizes the diameter of the centrallumen. Such a construction is particularly useful in steerable DMRcatheters in which an optic fiber, a puller wire, electrode leads, andan electromagnetic sensor cable all extend through the lumen of thecatheter body, but is also useful in other steerable catheterconstructions.

A preferred construction of the DMR catheter also includes a tubularspacer, between the polyimide stiffening tube and the tip section. Thespacer is made of a material less stiff than the material of thestiffening tube, e.g., polyimide, but more stiff than the material ofthe tip section, e.g., polyurethane. Teflon® is the presently preferredmaterial of the spacer.

In a preferred method for constructing the catheter, the stiffening tubeis inserted into the tubular outer wall until the distal end of thestiffening tube butts against the tubular spacer. Force is applied tothe proximal end of the stiffening tube which tube is then fixed inposition, e.g., by glue, to the outer wall. The application of force onthe proximal end of the stiffening tube assures that no gaps will formbetween the stiffening tube and tubular spacer or between the spacer andtip section as a result of repeated tip deflection.

In a steerable catheter construction comprising a stiffening tube andspacer, a puller wire preferably extends through a non-compressiblecompression coil which is fixed at its proximal end to the proximal endof the catheter body by means of a glue joint and fixed at its distalend to the proximal end of the tip section at a location distal to thespacer by means of a second glue joint. This arrangement preventscompression of the spacer during tip deflection which, in turn, permitsthe use of a thin walled spacer.

In yet another aspect to the invention, a control handle is providedwhich can be manipulated to deflect the tip section of the catheter. Thecontrol handle has a first member which is attached to the catheter bodyand a second member movable with respect to the first member, which isattached to the puller wire. In this arrangement, movement of the firstmember relative to the second member results in deflection of the tip.The handle comprises a guide tube through which the optic fiber extends.The guide tube is fixedly secured to the first or second member. Withinthis guide, the optic fiber is afforded lengthwise movement with respectto both the first and second members.

DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a side cross-sectional view of an embodiment of the catheterof the invention.

FIG. 2a is a side cross-sectional view of the catheter tip sectionshowing an embodiment having three lumens and showing the position ofthe electromagnetic mapping sensor and the optic fiber.

FIG. 2b is a side cross-sectional view of the catheter tip sectionshowing an embodiment having three lumens and showing the position ofthe electromagnetic mapping sensor and the puller wire.

FIG. 3 is a side cross-sectional view of the catheter body, includingthe junction between the catheter body and the tip section.

FIG. 4 is a side cross-sectional view of the catheter handle.

FIG. 5 is a transverse cross-sectional view of the catheter tip sectionalong line 5--5 showing an embodiment having three lumens.

FIG. 6 is a transverse cross-sectional view of the catheter body alongline 6--6.

FIG. 7 is a side cross-sectional view of the catheter body showing aninfusion tube.

FIG. 8 is a transverse cross-sectional view of the catheter tip sectionshowing an alternative embodiment having an infusion tube.

FIG. 9 is a cross-sectional view of a portion of the catheter tipsection showing a preferred means for anchoring the puller wire.

FIG. 10 is a top cross-sectional view of a preferred puller wire anchor.

FIG. 11 is a side cross-sectional view of a preferred puller wireanchor.

DETAILED DESCRIPTION

In a particularly preferred embodiment of the invention, there isprovided a catheter for use in direct myocardial revascularization(DMR). As shown in FIGS. 1-4, catheter 10 comprises an elongatedcatheter body 12 having proximal and distal ends, a tip section 14 atthe distal end of the catheter body 12, and a control handle 16 at theproximal end of the catheter body 12.

With reference to FIGS. 3 and 6, the catheter body 12 comprises anelongated tubular construction having a single, central or axial lumen18. The catheter body 12 is flexible, i.e., bendable, but substantiallynon-compressible along its length. The catheter body 12 can be of anysuitable construction and made of any suitable material. A presentlypreferred construction comprises an outer wall 22 made of a polyurethaneor nylon. The outer wall 22 comprises an imbedded braided mesh ofstainless steel or the like to increase torsional stiffness of thecatheter body 12 so that, when the control handle 16 is rotated, the tipsectionally of the catheter 10 will rotate in a corresponding manner.

The outer diameter of the catheter body 12 is not critical, but ispreferably no more than about 8 french. Likewise the thickness of theouter wall 22 is not critical. The inner surface of the outer wall 22 islined with a stiffening tube 20, which can be made of any suitablematerial, preferably polyimide. The stiffening tube, along with thebraided outer wall 22, provides improved torsional stability while atthe same time minimizing the wall thickness of the catheter, thusmaximizing the diameter of the single lumen. The outer diameter of thestiffening tube 20 is about the same as or slightly smaller than theinner diameter of the outer wall 22. Polyimide tubing is presentlypreferred because it may be very thin walled while still providing verygood stiffness. This maximizes the diameter of the central lumen 18without sacrificing strength and stiffness. Polyimide material istypically not used for stiffening tubes because of its tendency to kinkwhen bent. However, it has been found that, in combination with an outerwall 22 of polyurethane, nylon or other similar material, particularlyhaving a stainless steel braided mesh, the tendency for the polyimidestiffening tube 20 to kink when bent is essentially eliminated withrespect to the applications for which the catheter is used.

A particularly preferred catheter has an outer wall 22 with an outerdiameter of about 0.092 inch and an inner diameter of about 0.063 inchand a polyimide stiffening tube having an outer diameter of about 0.0615inch and an inner diameter of about 0.052 inch.

As shown in FIGS. 2a and 2b, the tip section 14 comprises a shortsection of tubing 19 having three lumens. The tubing 19 is made of asuitable non-toxic material which is preferably more flexible than thecatheter body 12. A presently preferred material for the tubing 19 isbraided polyurethane, i.e., polyurethane with an embedded mesh ofbraided stainless steel or the like. The outer diameter of the tipsection 14, like that of the catheter body 12, is preferably no greaterthan about 8 french. The size of the lumens is not critical. In aparticularly preferred embodiment, the tip section has an outer diameterof about 7 french (0.092 inch) and the first lumen 30 and second lumen32 are generally about the same size, having a diameter of about 0.022inch, with the third lumen 34 having a slightly larger diameter of about0.036 inch.

A preferred means for attaching the catheter body 12 to the tip section14 is illustrated in FIG. 3. The proximal end of the tip section 14comprises an outer circumferential notch 24 that receives the innersurface of the outer wall 22 of the catheter body 12. The tip section 14and catheter body 12 are attached by glue or the like. In thearrangement shown, a spacer 52 lies within the catheter body 12 betweenthe distal end of the stiffening tube 20 and the proximal end of the tipsection 14. The spacer 52 is preferably made of a material which isstiffer than the material of the tip section 14, e.g., polyurethane, butnot as stiff as the material of the stiffening tube 20, e.g., polyimide.A spacer made of Teflon® is presently preferred. A preferred spacer 52has a length of from about 0.25 inch to about 0.75 inch, more preferablyabout 0.5 inch. Preferably the spacer 52 has an outer and inner diameterabout the same as the outer and inner diameters of the stiffening tube20. The spacer 52 provides a transition in flexibility at the junctionof the catheter body 12 and catheter tip 14, which allows the junctionof the catheter body 12 and tip section 14 to bend smoothly withoutfolding or kinking.

The spacer 52 is held in place by the stiffening tube 20. The stiffeningtube 20, in turn, is held in place relative to the outer wall 22 by gluejoints 23 and 25 at the proximal end of the catheter body 12. In apreferred construction of the catheter body 12, a force is applied tothe proximal end of the stiffening tube 20 which causes the distal endof the stiffening tube 20 to firmly butt up against and compress thespacer 52. While under compression, a first glue joint is made betweenthe stiffening tube 20 and the outer wall 22 by a fast drying glue, e.g.Super Glue®. Thereafter a second glue joint is formed between theproximal ends of the stiffening tube 20 and outer wall 22 using a slowerdrying but stronger glue, e.g., polyurethane. Construction of thecatheter body 12 whereby the stiffening tube 20 and spacer 58 are undercompression has been found to be advantageous to prevent the formationof gaps between the stiffening tube 20 and spacer 58 or between spacer58 and the tip section 14 which might otherwise occur after repeated tipdeflections. Such gaps are undesirable because they cause the catheterto crease or fold over, hindering the catheter's ability to roll.

Extending through the single lumen 18 of the catheter body 12 are leadwires 40, an optic fiber 46, a sensor cable 74, and a compression coil44 through which a puller wire 42 extends. A single lumen 18 catheterbody is preferred over a multi-lumen body because it has been found thatthe single lumen 18 body permits better tip control when rotating thecatheter 10. The single lumen 18 permits the lead wires 40, the opticfiber 46, the sensor cable 74, and the puller wire 42 surrounded by thecompression coil 44 to float freely within the catheter body. If suchwires and cables were restricted within multiple lumens, they tend tobuild up energy when the handle 16 is rotated, resulting in the catheterbody 12 having a tendency to rotate back if, for example, the handle isreleased, or if bent around a curve, to flip over, either of which areundesirable performance characteristics.

The puller wire 42 is anchored at its proximal end to the control handle16 and anchored at its distal end to the tip section 14. The puller wire42 is made of any suitable metal, such as stainless steel or Nitinol,and is preferably coated with Teflon® or the like. The coating impartslubricity to the puller wire 42. The puller wire 42 preferably has adiameter ranging from about 0.006 to about 0.010 inches.

The compression coil 44 extends from the proximal end of the catheterbody 12 to the proximal end of the tip section 14. The compression coil44 is made of any suitable metal, preferably stainless steel. Thecompression coil 44 is tightly wound on itself to provide flexibility,i.e., bending, but to resist compression. The inner diameter of thecompression coil 44 is preferably slightly larger than the diameter ofthe puller wire 42. For example, when the puller wire 42 has a diameterof about 0.007 inches, the compression coil 44 preferably has an innerdiameter of about 0.008 inches. The Teflon® coating on the puller wire42 allows it to slide freely within the compression coil 44. Along itslength, the outer surface of the compression coil 44 is covered by aflexible, non-conductive sheath 26 to prevent contact between thecompression coil 44 and any of the lead wires 40, optic fiber 46 orsensor cable 74. A non-conductive sheath 26 made of polyimide tubing ispresently preferred.

The compression coil 44 is anchored at its proximal end to the proximalend of the stiffening tube 20 in the catheter body 12 by glue joint 29and at its distal end to the tip section 14 at a location distal to thespacer 52 by glue joint 50. Both glue joints 29 and 50 preferablycomprise polyurethane glue or the like. The glue may be applied by meansof a syringe or the like through a hole made between the outer surfaceof the catheter body 12 and the single lumen 18. Such a hole may beformed, for example, by a needle or the like that punctures the wall ofthe catheter body 12 and the stiffening tube 20 which is heatedsufficiently to form a permanent hole. The glue is then introducedthrough the hole to the outer surface of the compression coil 44 andwicks around the outer circumference to form a glue joint about theentire circumference of the compression coil 44.

The puller wire 42 extends into the second lumen 32 of the tip section14. The puller wire 42 is anchored to a tip electrode 36 or to the sideof the catheter tip section 14. With reference to FIGS. 2b and 3, withinthe tip section 14, and distal to the glue joint 51, the turns of thecompression coil are expanded longitudinally. Such expanded turns 47 areboth bendable and compressible and preferably extend for a length ofabout 0.5 inch. The puller wire 42 extends through the expanded turns 47then into a plastic, preferably Teflon®, sheath 81, which prevents thepuller wire 42 from cutting into the wall of the tip section 14 when thetip section 14 is deflected.

The distal end of the puller wire 42 may be anchored to the tipelectrode 36 by solder or the like, as shown in FIG. 2b or to the sidewall of the tip section 14. If attached to the side wall, an embodimentcomprising an anchor 80 fixedly attached to the distal end of the pullerwire 42 is preferred, as illustrated in FIGS. 9-11. In such anembodiment, the anchor is formed by a metal tube 82, e.g., a shortsegment of hypodermic stock, which is fixedly attached, e.g., bycrimping, to the distal end of the puller wire 42. The tube 82 has asection which extends a short distance beyond the distal end of thepuller wire 42. A cross-piece 84 made of a small section of stainlesssteel ribbon or the like is soldered or welded in a transversearrangement to the distal end of the tube 82, which is flattened duringthe operation. This creates a T-bar anchor 80. A notch 86 is created inthe side of the catheter tip section 14 resulting in an opening into thesecond lumen 32 carrying the puller wire 42. The anchor 80 lies withinthe notch 86. Because the length of the ribbon forming the cross-piece84 is longer than the diameter of the opening into the second lumen 32,the anchor 80 cannot be pulled completely into the second lumen 32. Thenotch 86 is then sealed with polyurethane or the like to give a smoothouter surface.

With reference to FIGS. 2a and 2b, at the distal end of the tip section14 is a tip electrode 36. Preferably the tip electrode 36 has a diameterabout the same as the outer diameter of the tubing 19. The tip electrode36 is connected to the tubing 19 by means of a plastic housing 21,preferably made of polyetheretherketone (PEEK). The proximal end of thetip electrode 36 is notched circumferentially and fits inside the distalend of the plastic housing 21 and is bonded to the housing 21 bypolyurethane glue or the like. The proximal end of the plastic housing21 is bonded with polyurethane glue or the like to the distal end of thetubing 19 of the tip section 14.

Mounted on the distal end of the plastic housing 21 is a ring electrode38. The ring electrode 38 is slid over the plastic housing 21 and fixedin place by glue or the like. If desired, additional ring electrodes maybe used and can be positioned over the plastic housing 21 or over theflexible tubing 19 of the tip section 14.

The tip electrode 36 and ring electrode 38 are each connected toseparate lead wires 40. The lead wires 40 extend through the third lumen34 of tip section 14, the catheter body 12, and the control handle 16,and terminate at their proximal end in an input jack (not shown) thatmay be plugged into an appropriate monitor (not shown). If desired, theportion of the lead wires 40 extending through the catheter body 12,control handle 16 and proximal end of the tip section 14 may be enclosedor bundled within a protective tube or sheath.

The lead wires 40 are attached to the tip electrode 36 and ringelectrode 38 by any conventional technique. Connection of lead wire 40to the tip electrode 36 is preferably accomplished by weld 43, as shownin FIG. 2b. Connection of a lead wire 40 to a ring electrode 38 ispreferably accomplished by first making a small hole through the plastichousing 21. Such a hole can be created, for example, by inserting aneedle through the plastic housing 21 and heating the needlesufficiently to form a permanent hole. A lead wire 40 is then drawnthrough the hole by using a microhook or the like. The ends of the leadwire 40 are then stripped of any coating and soldered or welded to theunderside of the ring electrode 38, which is then slid into positionover the hole and fixed in place with polyurethane glue or the like.

In a particularly preferred embodiment of the invention, a temperaturesensing means is provided for the tip electrode 36 and, if desired, thering electrode 38. Any conventional temperature sensing means, e.g., athermocouple or thermistor, may be used. With reference to FIG. 2b, apreferred temperature sensing means for the tip electrode 36 comprises athermocouple formed by an enameled wire pair. One wire of the wire pairis a copper wire 41, e.g., a number 40 copper wire which acts not onlyas part of the thermocouple, but as the electrode lead. The other wireof the wire pair is a constatan wire 45, e.g., a number 40 constatanwire, which gives support and strength to the wire pair. The wires 41and 45 of the wire pair are electrically isolated from each other exceptat their distal ends where they contact and are welded or soldered tothe tip electrode 36. Because it is desirable to monitor the temperatureof the tip electrode 36 at a site adjacent the distal end of the opticfiber 46, the thermocouple with a blind hole in the tip electrode 36 isfixed to the tip electrode 36 at the distal end of the blind hole asshown.

An optic fiber 46 for transmitting laser energy to create channels inthe heart tissue slidably extends through the control handle 16 andcatheter body 12 and into the first lumen 30 of the tip section 14. Asused herein, "channels" refers to percutaneous myocardial channels thatare formed in the heart tissue when the laser is fired. Preferredchannels are approximately 1.0 millimeter in diameter and up to about5.0 millimeters deep.

The distal end of the optic fiber 46 extends through an optic fiberlumen in the tip electrode 36 and is fixed to the tip electrode 36 byglue or the like. The distal end of the optic fiber 46 is flush with thedistal surface of the tip electrode. A connector (not shown) at theproximal end of the optic fiber 46 can be used to connect the proximalend of the optic fiber 46 to a laser (not shown). Any suitable laser canbe used. A presently preferred laser is a Shaplan Ho: YAG 2040 Laser.

The optic fiber 46 comprises a quartz core 48, a cladding made of dopedsilica or the like and a surrounding jacket 45. The jacket 45 can be ofany suitable material, preferably aluminum, but materials such as suchas nylon and polyimide may also be used. An 15 aluminum jacket 45 ispreferred as it tends to maximize the strength of the optic fiber 46 sothat when the optic fiber is bent, e.g., when the catheter tip 14 isdeflected, the quartz core does not break.

At the distal end of the optic fiber 46, the aluminum jacket 45 isstripped from the core 48. There are two principle reasons for this. Thefirst is to prevent material from the aluminum jacket (or any other typeof jacket) from breaking off into the heart chamber, particularly duringlaser transmission, which could lead to a stroke. The second is toelectrically isolate the aluminum jacket 45 from the tip electrode 36.This is a safety measure to assure that a short circuit does not occurbetween the jacket 45 and tip electrode 36 that could deliver apotentially lethal burst of high voltage to the patient during lasertransmission. A plastic, preferably polyimide, protective tube 47 isplaced in surrounding relation to the portion of the optic fiber 46covered by the jacket 45 that is situated within the tip electrode 36.The protective tube 47 prevents electrical contact between the jacket 45and the tip electrode 36. The protective tube 47 extends beyond thedistal end of the aluminum jacket 45 to help support the core 48. Theprotective tube 47 cannot extend too close to the distal tip of theoptic fiber 46, however, because it would melt when the laser is fired.The protective tube 47 is fixed to the tip electrode 36 by glue or thelike.

An electromagnetic sensor 72 is contained within the distal end of thetip section 14. The electromagnetic sensor 72 is connected by means ofelectromagnetic sensor cable 74, which extends through the third lumen34 of the tip section 14 through the catheter body 12 into the controlhandle 16. The electromagnetic sensor cable 74 comprises multiple wiresencased within a plastic covered sheath. In the control handle 16, thewires of the sensor cable 74 are connected to a circuit board 64. Thecircuit board 64 amplifies the signal received from the electromagneticsensor and transmits it to a computer in a form understandable by thecomputer. Also, because the catheter is designed for single use only,the circuit board contains an EPROM chip which shuts down the circuitboard after the catheter has been used. This prevents the catheter, orat least the electromagnetic sensor, from being used twice. A suitableelectromagnetic sensor is described, for example, in U.S. Pat. No.4,391,199, which is incorporated herein by reference. A preferredelectromagnetic mapping sensor 72 is manufactured by Biosense Ltd.Israel and marketed under the trade designation NOGA. To use theelectromagnetic sensor 72, the patient is placed in a magnetic fieldgenerated, for example, by situating under the patient a pad containingcoils for generating a magnetic field. A reference electromagneticsensor is fixed relative to the patient, e.g., taped to the patient'sback, and the DMR catheter containing a second electromagnetic sensor isadvanced into the patient's heart. Each sensor comprises three smallcoils which in the magnetic field generate weak electrical signalsindicative of their position in the magnetic field. Signals generated byboth the fixed reference sensor and the second sensor in the heart areamplified and transmitted to a computer which analyzes the signals andthen displays the signals on a monitor. By this method, the preciselocation of the sensor in the catheter relative to the reference sensorcan be ascertained and visually displayed. The sensor can also detectdisplacement of the catheter that is caused by contraction of the heartmuscle.

Using this technology, the physician can visually map a heart chamber.This mapping is done by advancing the catheter tip into a heart chamberuntil contact is made with the heart wall. This position is recorded andsaved. The catheter tip is then moved to another position in contactwith the heart wall and again the position is recorded and saved.

The electromagnetic mapping sensor 72 can be used alone or morepreferably in combination with the tip electrode 36 and ring electrode38. By combining the electromagnetic sensor 72 and electrodes 36 and 38,a physician can simultaneously map the contours or shape of the heartchamber, the electrical activity of the heart, and the extent ofdisplacement of the catheter and hence identify the presence andlocation of the ischemic tissue. Specifically, the electromagneticmapping sensor 72 is used to monitor the precise location of the tipelectrode in the heart and the extent of catheter displacement. The tipelectrode 36 and ring electrode 38 are used to monitor the strength ofthe electrical signals at that location. Healthy heart tissue isidentified by strong electrical signals in combination with strongdisplacement. Dead or diseased heart tissue is identified by weakelectrical signals in combination with dysfunctional displacement, i.e.,displacement in a direction opposite that of healthy tissue. Ischemic,or hibernating or stunned, heart tissue is identified by strongelectrical signals in combination with impaired displacement. Hence, thecombination of the electromagnetic mapping sensor 72 and tip and ringelectrodes 36 and 38 is used as a diagnostic catheter to determinewhether and where use of the laser is appropriate. Once the presence andlocation of ischemic tissue has been identified, the DMR catheter can bedeflected so that the optic fiber is normal, i.e., at a right angle, tothe ischemic tissue, and laser energy is fired through the optic fiberin coordination with the heart activity, e.g. during systole, to createa channel in the ischemic tissue, for example, as described in U.S. Pat.Nos. 5,554,152, 5,389,096, and 5,380,316, the disclosures of which areincorporated herein by reference. This procedure is repeated to createmultiple channels.

It is understood that, while it is preferred to include bothelectrophysiology electrodes and an electromagnetic sensor in thecatheter tip, it is not necessary to include both. For example, a DMRcatheter having an electromagnetic sensor but no electrophysiologyelectrodes may be used in combination with a separate mapping cathetersystem. A preferred 20 mapping system includes a catheter comprisingmultiple electrodes and an electromagnetic sensor, such as the NOGA-STARcatheter marketed by Cordis Webster, Inc., and means for monitoring anddisplaying the signals received from the electrodes and electromagneticsensor, such as the Biosense-NOGA system, also marketed by CordisWebster, Inc.

The electrode lead wires 40, optic fiber 46 and electromagnetic sensorcable 74 must be allowed some longitudinal movement within the catheterbody so that they do not break when the tip section 14 is deflected. Toprovide for such lengthwise movement, there are provided tunnels throughthe glue joint 50, which fixes the proximal end of the compression coil44 inside the catheter body 12. The tunnels are formed by transfer tubes27, preferably made of short segments of polyimide tubing. In theembodiment shown in FIG. 3, there are two transfer tubes 27 for the gluejoint 50. Each transfer tube is approximately 60 mm long and has anouter diameter of about 0.021 inch and an inner diameter of about 0.019inch. Extending through one transfer tube 27 are the lead wires 40 andthe electromagnetic sensor cable 74. Extending through the othertransfer tube 27 is the optic fiber 46.

An additional transfer tube 29 is located at the joint between the tipsection 14 and the catheter body 12. Extending through this transfertube is the optic fiber 46. This transfer tube 29 provides a tunnelthrough the glue joint formed when the tip section 14 is glued to thecatheter body 12. It is understood that the number of transfer tubes mayvary as desired.

Longitudinal movement of the puller wire 42 relative to the catheterbody 12, which results in deflection of the tip section 12, isaccomplished by suitable manipulation of the control handle 16. Thedistal end of the control handle 16 comprises a piston 54 with a thumbcontrol 56 for manipulating the puller wire 42. The proximal end of thecatheter body 12 is connected to the piston 54 by means of a shrinksleeve 28.

The optic fiber 46, puller wire 42, lead wires 40 and electromagneticsensor cable 74 extend through the piston 54. The puller wire 42 isanchored to an anchor pin 36, located proximal to the piston 54. Thelead wires 40 and electromagnetic sensor cable 74 extend though a firsttunnel 58, located near the side of the control handle 16. Theelectromagnetic sensor cable 74 connects to the circuit board 64 in theproximal end of the control handle 16. Wires 80 connect the circuitboard 64 to a computer and imaging monitor (not shown).

The optic fiber 46 extends through a guide tube 66, preferably made ofpolyurethane, and is afforded longitudinal movement therein. Thepolyurethane guide tube 66 is anchored to the piston 54, preferably byglue at glue joint 53. This allows the optic fiber 46 longitudinalmovement within the control handle 16 so that it does not break when thepiston 54 is adjusted to manipulate the puller wire 42. Within thepiston 54, the puller wire 42 is situated within a transfer tube 27, andthe electromagnetic sensor cable 74 and lead wires 40 are situatedwithin another transfer tube 27 to allow longitudinal movement of thewires and cable near the glue joint 53.

The optic fiber 46 and guide tube 66 extend through a second tunnel 60situated near the side of the control handle 16 opposite the anchor pin36. To avoid undesirable bending of the optic fiber 46, a space 62 isprovided between the proximal end of the piston 54 and the distal end ofthe second tunnel 60. Preferably the space 62 has a length of at least0.50 inch and more preferably about from about 0.60 inch to about 0.90inch.

In the proximal end of the control handle 16, the optic fiber 46 and thepolyurethane guide tube 66 extend through a second larger plastic guidetube 68, preferably made of Teflon®, which affords the guide tube 66 andoptic fiber 46 longitudinal slidable movement. The second guide tube 68is anchored to the inside of the control handle 16 by glue or the likeand extends proximally beyond the control handle 16. The second guidetube 68 protects the fiber 46 both from contact with the circuit board64 and from any sharp bends as the guide tube 66 and optic fiber 46emerge from the control handle 16.

In another preferred catheter constructed in accordance with the presentinvention, there is provided an infusion tube 76 for infusing fluids,including drugs such as fibroblast growth factor (FGP), vascularendothelial growth factor (VEGP), thromboxane-A2 or protein kinase-C.These are drugs that initiate or promote angiogenesis. FGP and VEGP workdirectly to initiate the formation of new blood vessels. Thromboxane-A2and protein kinase-C work indirectly to form new blood vessels. They arereleased by blood platelets during clot formation and have specificreceptor sites which release FGF and VEGF.

Other preferred drugs that may be infused include those which minimizethe effect of foreign body reaction and extend the potency of thecreated channels. Drugs such as dexamethasone in various forms, e.g.,dexamethasone sodium phosphate and dexamethasone acetate, can bedelivered to sites to reduce inflammation associated with trauma andforeign body reaction which lead to the formation of fibrosis andcollagen capsules which, in turn, close the created channels.

It is apparent that other drugs may be infused as desired. Moreover,saline, or the like, may be infused for controlling the temperature ofthe tip electrode. The infusion tube 76 may even be used for collectingtissue or fluid samples. The infusion tube 76 may be made of anysuitable material, and is preferably made of polyimide tubing.

With reference to FIGS. 7 and 8, there is shown a catheter 10 having aninfusion tube 76. The catheter 10 comprises a single lumen catheter body12 as described above and a catheter tip section 14 comprising fourlumens. To accommodate four lumens in the tip section, the diameter ofthe catheter may need to be increased slightly. The infusion tube 76extends through the catheter body 12 and into the fourth lumen 77 of thetip section 14. The distal end of the infusion tube 76 extends into anopening or passage through the tip electrode 36 and is fixed, e.g., byglue, to the tip electrode 36. The passage in the tip electrode 36 maybe straight or branched as desired. Alternatively, the infusion tube 76can replace the optic fiber 46 in the first lumen 30 of the triple lumentip section 14 in the embodiment described above.

The proximal end of the infusion tube 76 extends out of a sealed openingin the side wall of the catheter body and terminates in a luer hub orthe like. Alternatively, the infusion tube 76 may extend through thecontrol handle and terminate in a luer hub or the like at a locationproximal to the handle. In this arrangement, fluids, including drugs topromote revascularization, may be infused into the heart at the preciselocation of the revascularization procedure.

In another embodiment, as shown in FIG. 8, a guide wire hole 78 isprovided at the distal end of the tip section 14. The guide wire hole 78extends from the side of the tip electrode 36 to the distal end of thetip electrode at an angle of about 30° to the longitudinal axis of thetip electrode. The guide wire hole 78 allows a guide wire (not shown) tobe introduced into the heart and the catheter 10 to be passed over theguide wire until it is in the proper location within the heart.Generally, to get the guide wire into the heart, an introducing sheathis passed into the heart and then the guide wire is introduced into theheart from the introducing sheath.

In another preferred embodiment constructed in accordance with thepresent invention, two or more puller wires are provided to enhance theability to manipulate the tip section. In such an embodiment, a secondpuller wire and a surrounding second compression coil extend through thecatheter body and into separate off-axis lumens in the tip section. Thelumens of the tip section receiving the puller wires may be in adjacentquadrants. The first puller wire is preferably anchored proximal to theanchor location of the second puller wire. The second puller wire may beanchored to the tip electrode or may be anchored to the wall of the tipsection adjacent the distal end of tip section.

The distance between the distal end of the compression coils and theanchor sites of each puller wire in the tip section determines thecurvature of the tip section 14 in the direction of the puller wires.For example, an arrangement wherein the two puller wires are anchored atdifferent distances from the distal ends of the compression coils allowsa long reach curve in a first plane and a short reach curve in a plane90° from the first, i.e., a first curve in one plane generally along theaxis of the tip section before it is deflected and a second curve distalto the first curve in a plane transverse, and preferably normal to thefirst plane. The high torque characteristic of the catheter tip section12 reduces the tendency for the deflection in one direction to deformthe deflection in the other direction.

As an alternative to the above described embodiment, the puller wiresmay extend into diametrically opposed off-axis lumens in the tipsection. In such an embodiment, each of the puller wires may be anchoredat the same location along the length of the tip section, in which casethe curvatures of the tip section in opposing directions are the sameand the tip section can be made to deflect in either direction withoutrotation of the catheter body.

A particularly preferred catheter construction comprising multiplepuller wires including control handle construction is disclosed inpending patent application entitled Omni-Directional Steerable Catheter,naming as inventor Wilton W. Webster, Jr. Appl. Ser. No. 08/924,611filed concurrently herewith and incorporated hereby by reference. Suchapplication describes a suitable control handle for manipulating two ormore puller wires. The described control handle includes a centralpassage that may be expanded to accommodate the electrode lead wires,electromagnetic sensor cable, optic fiber and even infusion tube.Further, an extension of the handle may be provided to house the circuitbound for the electromagnetic sensor, e.g., in the same manner as shownin FIG. 4 herein.

The preceding description has been presented with reference to presentlypreferred embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention.

Accordingly, the foregoing description should not be read as pertainingonly to the precise structures described and illustrated in theaccompanying drawings, but rather should be read consistent with and assupport to the following claims which are to have their fullest and fairscope.

I claim:
 1. A steerable direct myocardial revascularization cathetercomprising:a catheter body having an outer wall, proximal and distalends, and at least one lumen extending therethrough; a control handlefixedly attached to the proximal end of the catheter body; a tip sectioncomprising flexible tubing having proximal and distal ends and at leastone off-axis lumen extending therethrough, the proximal end of the tipsection being fixedly attached to the distal end of the catheter body; atip electrode mounted at the distal end of the tip section, said tipelectrode having a distal face and an optic fiber lumen therethrough; anelectrode lead wire electrically connected to the tip electrode, saidlead wire extending through a lumen in the tip section, through a lumenin the catheter body and into the control handle; an optic fibercomprising a core, a cladding and a protective jacket and having adistal end and a proximal end, said optic fiber extending through alumen in the catheter body and a lumen in the tip section and into theoptic fiber lumen of the tip electrode, said distal end of the opticfiber being substantially flush with the distal face of the tipelectrode; a protective tube surrounding at least a portion of the opticfiber that extends in the optic fiber lumen in the tip electrode; andmeans for deflecting the tip section by manipulation of the controlhandle.
 2. A catheter according to claim 1 wherein the jacket isstripped from the optic fiber core at its distal end.
 3. A catheteraccording to claim 1 wherein the protective jacket comprises aluminum.4. A catheter according to claim 3 wherein the aluminum jacket isstripped from the optic fiber core at its distal end.
 5. A catheteraccording to claim 1 wherein the protective tube is a polyimide tube. 6.A catheter according to claim 1 wherein the distal end of the opticfiber is fixedly secured within the optic fiber lumen of the tipelectrode.
 7. A catheter according to claim 1 wherein the catheter bodyhas a single lumen extending therethrough.
 8. A catheter according toclaim 1 wherein the tip section has three lumens extending therethrough.9. A catheter according to claim 1, further comprising at least one ringelectrode fixedly secured in surrounding relation to the tip section.10. A catheter according to claim 1, further comprising anelectromagnetic mapping sensor in the distal portion of the tip sectionfor producing electrical signals indicative of the location of theelectromagnetic mapping sensor.
 11. A catheter according to claim 10,further comprising a sensor cable electrically attached to theelectromagnetic mapping sensor and extending through a lumen in the tipsection, through a lumen in the catheter body and into the controlhandle, wherein the sensor cable is electrically attached to a circuitboard situated within the control handle.
 12. A catheter according toclaim 1 wherein the outer wall comprises polyurethane or nylon.
 13. Acatheter according to claim 1, wherein the outer wall comprises animbedded braided stainless steel mesh.
 14. A catheter according to claim12 wherein a braided stainless steel mesh is imbedded in thepolyurethane or nylon.
 15. A catheter according to claim 1 wherein theouter wall has an outer diameter of about 0.092 inch and an innerdiameter of about 0.063 inch.
 16. A catheter according to claim 1,wherein the catheter body further comprises an inner stiffening tubelining the outer wall, said stiffening tube having a distal end and aproximal end.
 17. A catheter according to claim 16 wherein thestiffening tube comprises polyimide.
 18. A catheter according to claim16 wherein the stiffening tube has an outer diameter of about 0.0615inch and an inner diameter of about 0.052 inch.
 19. A catheter accordingto claim 16, further comprising a spacer between the distal end of thestiffening tube and the proximal end of the tip section.
 20. A catheteraccording to claim 1 wherein the flexible tubing of the tip section ismade of polyurethane.
 21. A catheter according to claim 1 wherein theflexible tubing of the tip section comprises an imbedded braidedstainless steel mesh.
 22. A catheter according to claim 20 wherein thepolyurethane tubing comprises an imbedded braided stainless steel mesh.23. A catheter according to claim 1 further comprising a tubular housinghaving a distal and proximal ends, wherein the distal end of the tubularhousing is fixedly attached to the proximal end of the tip electrode andthe proximal end of the tubular housing is fixedly attached to thedistal end of the flexible tubing of the tip section.
 24. A catheteraccording to claim 23 wherein the tubular housing is made of PEEK.
 25. Acatheter according to claim 1 wherein the control handle comprises afirst member fixedly attached to the proximal end of the catheter bodyand a second member that is movable relative to the first member.
 26. Acatheter according to claim 25 wherein the deflecting means comprises apuller wire having a proximal end and a distal end, the puller wireextending from the control handle, through the catheter body and intothe off axis lumen in the tip section, wherein the distal end of thepuller wire is fixedly secured within the tip section and the proximalend of the puller wire is fixedly secured to the second member of thecontrol handle, whereby manipulation of the first member of the controlhandle relative to the second member of the control handle moves thepuller wire relative to the catheter body, resulting in deflection ofthe tip section.
 27. A catheter according to claim 26 wherein thedeflecting means further comprises a compression coil situated in thecatheter body in surrounding relation to the puller wire and extendinginto the off axis lumen in the tip section.
 28. A catheter according toclaim 27 wherein the compression coil is anchored to the catheter at theproximal end of the catheter body and at the proximal end of the tipsection.
 29. A catheter according to claim 1, further comprising aninfusion tube having a proximal end and a distal end, said infusion tubeextending through a lumen in the catheter body and a lumen in the tipsection, wherein the distal end of the infusion tube is anchored in thetip electrode and wherein the proximal end of the infusion tube extendsoutside the catheter for receiving fluids.
 30. A catheter according toclaim 1, further comprising a temperature sensing means.
 31. A catheteraccording to claim 30 wherein the temperature sensing means comprises athermocouple formed by an enameled wire pair comprising a copper wireand a constantan wire, wherein the enameled wire pair extends through alumen in the catheter body and a lumen in the tip section and is fixedlyattached in the distal end of the tip section.